PO number is not unique while saving in Draft.
I am getting problems in PO number when it is saved as draft and sent for Approval. I have 5 users entering PO at the same time and since POs are being sent for approvals, it is being saved as Drafts. so the duplication of PO Draft number is the issue.
While saving the the POs in draft, same numbers are being generated until and unless we get approval and we add it in the system.